From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx180.postini.com [74.125.245.180]) by kanga.kvack.org (Postfix) with SMTP id B2D226B0005 for ; Wed, 10 Apr 2013 03:15:00 -0400 (EDT) Date: Wed, 10 Apr 2013 17:14:53 +1000 From: Michael Ellerman Subject: Re: [PATCH -V5 06/25] powerpc: Reduce PTE table memory wastage Message-ID: <20130410071453.GB24786@concordia> References: <1365055083-31956-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1365055083-31956-7-git-send-email-aneesh.kumar@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1365055083-31956-7-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Aneesh Kumar K.V" Cc: benh@kernel.crashing.org, paulus@samba.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org On Thu, Apr 04, 2013 at 11:27:44AM +0530, Aneesh Kumar K.V wrote: > From: "Aneesh Kumar K.V" > > We allocate one page for the last level of linux page table. With THP and > large page size of 16MB, that would mean we are wasting large part > of that page. To map 16MB area, we only need a PTE space of 2K with 64K > page size. This patch reduce the space wastage by sharing the page > allocated for the last level of linux page table with multiple pmd > entries. We call these smaller chunks PTE page fragments and allocated > page, PTE page. This is not compiling for me: arch/powerpc/mm/mmu_context_hash64.c:118:3: error: implicit declaration of function 'reset_page_mapcount' And similar. cheers -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org